High fat diet may cause changes in the brain: study

October 24, 2016

Washington, Oct 24: In a recent study, scientists have discovered a new mechanism that regulates obesity. The study shows that this new mechanism can potentially be targeted to treat obesity.

highfatSenior author of the study Makoto Fukuda said, "It's well known that the brain is involved in the development of obesity, but how a high-fat diet changes the brain so it triggers the accumulation of body fat is still unclear."

The team studied the mouse Rap1 gene, which is expressed in a variety of tissues, including the brain where it is involved in functions such as memory and learning. Little was known, however, of the role brain Rap1 plays in energy balance.

To explore the role Rap1 plays in a mouse model, the scientists selectively deleted the Rap1 gene in a group of neurons in the hypothalamus, a region of the brain that is involved in regulating whole-body metabolism.

The scientists had two groups of mice. In one group, the mice were genetically engineered to lack the Rap1 gene, while the control group had a functional Rap 1 gene. Then, the scientists fed the mice in both groups a high-fat diet in which 60 percent of the calories came from fat.

As expected, the control mice with a working Rap1 gene gained weight, but, in comparison, the mice that lacked Rap 1 had markedly reduced body weight and less body fat. Interestingly, when both groups of mice were fed a normal diet, both showed similar weights and body fat.

The scientists then looked closer at why the mice lacking the Rap1 gene had not gained weight despite eating a high-fat diet.

"We observed that the mice lacking Rap1 were not more physically active. However, they ate less and burned more body fat than mice with Rap1," said Fukuda.

Adding, "These observations were associated with the hypothalamus producing more of a hormone that reduces appetite, called POMC, and less of hormones that stimulate appetite, called NPY and AgRP." These mice also had lower levels of blood glucose and insulin than controls.

The scientists also were interested in studying whether leptin changed in mice lacking Rap1.

Leptin, the 'satiety hormone' produced by fatty tissue, helps regulate body weight by inhibiting appetite. Obese people, however, do not respond to leptin's signals of satiety, and the blood levels of leptin are higher than those in non-obese people. Leptin resistance is a hallmark of human obesity.

Mice that lacked Rap1 and ate a high-fat diet, on the other hand, did not develop leptin resistance; they were able to respond to leptin and this was reflected in the hormone's lower blood levels.

The team also tested the effect of inhibiting Rap1 with drugs instead of deleting the gene on mice on a high-fat diet. The scientists inhibited RAP1 action with inhibitor ESI-05.

"When we administered ESI-05 to obese mice, we restored their sensitivity to leptin to a level similar to that in mice eating a normal diet. The mice ate less and lost weight," he said.

The scientists have shown a new mechanism by which the brain can affect the development of obesity triggered by consuming a high-fat diet.

Consuming a high-fat diet results in changes in the brain that increase Rap1 activity, which in turn leads to a decreased sensitivity to leptin, and this sets the body on a path to obesity.

"This new mechanism involving Rap1 in the brain may represent a potential therapeutic target for treating human obesity in the future," said Fukuda.

The study appeared in Cell Reports today.

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Agencies
February 11,2020

Using smartphone for long hours every day may do you more harm than you can probably think of. Researchers have found that spending a lot of time with the device and on social media may lead to mental distress and suicidality among adolescents.

The findings, published in the journal CMAJ (Canadian Medical Association Journal) contains guidance for physicians, parents and teachers on how to help teenagers manage smartphone and social media use for a healthy balance between sleep, academic work, social activity, interpersonal relationships and online activity.

"Physicians, teachers and families need to work together with youth to decrease possible harmful effects of smartphones and social media on their relationships, sense of self, sleep, academic performance, and emotional well-being," said lead author of the study Elia Abi-Jaoude from Toronto Western Hospital in Canada.

This review of evidence, led by the Hospital for Sick Children (SickKids), focuses on smartphone use and does not consider online gaming.

"For adolescents today, who have not known a world without social media, digital interactions are the norm, and the potential benefits of online access to productive mental health information -- including media literacy, creativity, self-expression, sense of belonging and civic engagement -- as well as low barriers to resources such as crisis lines and Internet-based talking therapies cannot be discounted," the authors wrote.

The researchers recommend that doctors should ask teenagers to reduce social media use rather than eradicate it completely and encourage parents to be part of the conversations.

Parents should discuss appropriate smartphone use with teenagers to determine together how to reduce risks and set boundaries.

A recent poll from the US indicates that 54 per cent of teenagers think they spend too much time on their smartphones and about half said they were cutting back on usage.

"Encouragingly, youth are increasingly recognising the negative impact of social media on their lives and starting to take steps to mitigate it," the authors wrote.

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Agencies
February 7,2020

Birmingham, Feb 7: According to a new study, social media users are more likely to eat healthy or junk food after getting influenced by their peer group.

The research published in the scientific journal 'Appetite' found that study participants ate an extra fifth of a portion of fruit and vegetables themselves for every portion they thought their social media peers ate. So, if they believed their friends got their 'five a day' of fruit and veg, they were likely to eat an extra portion themselves.

On the other hand, Facebook users were found to consume an extra portion of unhealthy snack foods and sugary drinks for every three portions they believed their online social circles did.
The findings suggested that people eat around a third more junk food if they think their friends also indulge in the same.

The Aston University researchers said the findings provide the first evidence to suggest our online social circles could be implicitly influencing our eating habits, with important implications for using 'nudge' techniques on social media to encourage healthy eating.

Researchers asked 369 university students to estimate the amount of fruit, vegetables, 'energy-dense snacks' and sugary drinks their Facebook peers consumed on a daily basis.

The information was cross-referenced with the participants' own actual eating habits and showed that those who felt their social circles 'approved' of eating junk food consumed significantly more themselves. Meanwhile, those who thought their friends ate a healthy diet ate more portions of fruit and veg. Their perceptions could have come from seeing friends' posts about the food and drink they consumed, or simply a general impression of their overall health.

There was no significant link between the participants' eating habits and their Body Mass Index (BMI), a standard measure of healthy weight, however. The researchers said the next stage of their work would track a participant group over time to see whether the influence of social media on eating habits had a longer-term impact on weight.

The most recent figures from the NHS's Health Survey for England showed that in 2018 only 28 percent of adults were eating the recommended five portions of fruit and vegetables per day. In Wales, this was 24 percent, in Scotland 22 percent and in Northern Ireland around 20 percent. Children and young people across the UK had even lower levels of fruit and veg consumption.

Aston University health psychology Ph.D. student Lily Hawkins, who led the study alongside supervisor Dr. Jason Thomas, said: "This study suggests we may be influenced by our social peers more than we realize when choosing certain foods. We seem to be subconsciously accounting for how others behave when making our own food choices. So if we believe our friends are eating plenty of fruit and veg we're more likely to eat fruit and veg ourselves. On the other hand, if we feel they're happy to consume lots of snacks and sugary drinks, it can give us a license to overeat foods that are bad for our health. The implication is that we can use social media as a tool to 'nudge' each other's eating behavior within friendship groups, and potentially use this knowledge as a tool for public health interventions."

"With children and young people spending a huge amount of time interacting with peers and influencers via social media, the important new findings from this study could help shape how we deliver interventions that help them adopt healthy eating habits from a young age and stick with them for life," said professor Claire Farrow.

A dietitian called Aisling Pigott further mentioned that "Research such as this demonstrates how we are influenced by online perceptions about how others eat. The promotion of positive health messages across social media, which are focused on promoting healthy choices and non-restrictive relationships with food and body, could nudge people into making positive decisions around the food they eat."

"We do have to be mindful of the importance of 'nudging' positive behaviors and not 'shaming' food choices on social media as a health intervention. We know that generating guilt around food is not particularly helpful when it comes to lifestyle change and maintenance," Aisling added.

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Agencies
May 8,2020

As Europe and the US loosen their lockdowns against the coronavirus, health experts are expressing growing dread over what they say is an all-but-certain second wave of deaths and infections that could force governments to clamp back down.

"We are risking a backslide that will be intolerable," said Dr Ian Lipkin of Columbia University's Center for Infection and Immunity.

Around the world, German authorities began drawing up plans in case of a resurgence of the virus. Experts in Italy urged intensified efforts to identify new victims and trace their contacts. And France, which has not yet eased its lockdown, has already worked up a "reconfinement plan" in the event of a new wave.

"There will be a second wave, but the problem is to which extent. Is it a small wave or a big wave? It is too early to say," said Olivier Schwartz, head of the virus unit at France's Pasteur Institute.

In the US, with about half of the states easing their shutdowns to get their economies restarted and cellphone data showing that people are becoming restless and increasingly leaving home, public health authorities are worried.

Many states have not put in place the robust testing that experts believe is necessary to detect and contain new outbreaks. And many governors have pressed ahead before their states met one of the key benchmarks in the Trump administration's guidelines for reopening -- a 14-day downward trajectory in new illnesses and infections.

"If we relax these measures without having the proper public health safeguards in place, we can expect many more cases and, unfortunately, more deaths," said Josh Michaud, associate director of global health policy with the Kaiser Family Foundation in Washington.

Cases have continued to rise steadily in places such as Iowa and Missouri since the governors began reopening, while new infections have yo-yoed in Georgia, Tennessee and Texas.

Lipkin said he is most worried about two things: the reopening of bars, where people crowd together and lose their inhibitions, and large gatherings such as sporting events, concerts and plays. Preventing outbreaks will require aggressive contact tracing powered by armies of public health workers hundreds of thousands of people strong, which the US does not yet have, Lipkin said.

Worldwide the virus has infected more than 36 lakh people and killed over a quarter-million, according to a tally by Johns Hopkins University that experts agree understates the dimensions of the disaster because of limited testing, differences in counting the dead and concealment by some governments.

The US has recorded over 70,000 deaths and 12 lakh confirmed infections, while Europe has reported over 140,000 dead.

This week, the researchers behind a widely cited model from the University of Washington nearly doubled their projection of deaths in the US to around 134,000 through early August, in large part because of the easing of state stay-at-home restrictions. Newly confirmed infections per day in the US exceed 20,000 and deaths per day are running well over 1,000.

In hard-hit New York City, which has managed to bring down deaths dramatically even as confirmed infections continue to rise around the rest of the country, Mayor Bill de Blasio warned that some states may be reopening too quickly.

"My message to the rest of the country is learn from how much effort, how much discipline it took to finally bring these numbers down and follow the same path until you are sure that it is being beaten back," he said on CNN, "or else, if this thing boomerangs, you are putting off any kind of restart or recovery a hell of a lot longer."

A century ago, the Spanish flu epidemic's second wave was far deadlier than its first, in part because authorities allowed mass gatherings from Philadelphia to San Francisco.

"It is clear to me that we are in a critical moment of this fight. We risk complacency and accepting the preventable deaths of 2,000 Americans each day," epidemiologist Caitlin Rivers, a professor at Johns Hopkins, told a House subcommittee in Washington.

President Donald Trump, who has pressed hard to ease the restrictions that have throttled the economy and thrown more than three crore Americans out of work, pulled back Wednesday on White House plans revealed a day earlier to wind down the coronavirus task force.

He tweeted that the task force will continue meeting indefinitely with a "focus on SAFETY & OPENING UP OUR COUNTRY AGAIN".

Underscoring those economic concerns, the European Union predicted the worst recession in its quarter-century history. And the US unemployment rate for April, which comes out on Friday, is expected to hit a staggering 16 per cent, a level last seen during the Great Depression of the 1930s.

Governors continue to face demands, even lawsuits, to reopen. In Michigan, where armed demonstrators entered the Capitol last week, the Republican-led Legislature sued Democratic Governor Gretchen Whitmer, asking a judge to declare invalid her stay-at-home order, which runs at least through May 15.

In hard-hit Italy, which has begun easing restrictions, Dr Silvio Brusaferro, president of the Superior Institute of Health, urged "a huge investment" of resources to train medical personnel to monitor possible new cases of the virus, which has killed about 30,000 people nationwide.

He said that contact-tracing apps which are being built by dozens of countries and companies are not enough to manage future waves of infection.

German Chancellor Angela Merkel said after meeting with the country's 16 governors that restaurants and other businesses will be allowed to reopen in the coming weeks but that regional authorities will have to draw up a "restriction concept" for any county that reports 50 new cases for every 100,000 inhabitants within a week.

Lothar Wieler, head of Germany's national disease control centre, said scientists "know with great certainty that there will be a second wave" of infections.

Britain, with over 30,000 dead, the second-highest death toll in the world behind the US, plans to extend its lockdown but has begun recruiting 18,000 people to trace contacts of those infected.

In other developments, the US Centers for Disease Control and Prevention said nearly 5,000 coronavirus illnesses and at least 88 deaths have been reported among inmates in American jails and prisons. An additional 2,800 cases and 15 deaths were reported among guards and other staff members.

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